Engine camshaft and accessory drive

ABSTRACT

An overhead camshaft engine has a toothed belt drive wherein the back side of the belt is grooved to mate with multiple vee grooves and ridges of the water pump and fan drive pulley. The water pump is laterally movable on the engine block to provide a belt tension adjustment. The arrangement provides positive drive of the camshaft with nonpositive drive of the water pump and fan to permit slippage of the latter during excessive torque loadings.

Unitd States Paten [5 6] References Cited UNITED STATES PATENTS1,195,441 8/1916 Caron....,......................

[72] Inventor BorisJ.Mitchel|l Birmingham, Mich. 25,229

1/1925 Sparks..... 4/1926 Freitag.........,............... 2,010,0568/1935 Brush....................

:Mmm h m el fl mcw maeue SCBBF 59488 45666 99999 11111 Ill// 272 1959033 700045 Z AdrnU Z 040 22 992668 .J 223333 Appl. No. 22 FiledApr.2,l970 Patented Sept. 7, 1971 [73] Assignee General MotorsCorporation Detroit, Mich.

12/1969 Buchwald.................::..

Primary Examiner-Al Lawrence Smith [54] ENGHNE CAMSHAFI AND ACCESSORYDRIVE 2 Claims, 3 Drawing Figs.

123/4147, 17, 123/ l 123/195 drive wherein the back side of the belt isgrooved to mate with I 74/231 C, 74/242.14 R multiple vee grooves andridges of the water pump and fan int.

F011) 5/112, drive pulley. The water pump is laterally movable on theengine block to provide a belt tension adjustment. The arrange Field of123/9027, ment provides positive drive of the camshaft with nonpositive74/242-14 drive of the water pump and fan to permit slippage of thelatter during excessive torque loadings.

R, 231 R, 231 C, 234

ENGINE CAMSIIAFI AND ACCESSORY DRIVE FIELD OF THE INVENTION Thisinvention relates to camshaft and accessory drives for internalcombustion engines and, in its more particular aspects, to a drivearrangement which provides positive drive of the camshaft andnonpositive drive of the engine water pump and fan.

SUMMARY OF THE INVENTION The present invention provides a camshaft drivearrangement for an overhead camshaft engine which utilizes a cog ortoothed belt to positively connect the crankshaft and camshaft fordriving the latter. The back of the cog belt is provided with multiplelongitudinally extending grooves which drivingly engage the drive pulleyof the engine water pump and fan to drive these accessories in anonpositive manner. The engine water pump is adjustably mounted on theengine block to provide an adjustment for tensioning the cog belt and isalso arranged to deliver coolant directly to the coolant cavity withclearance being provided for the required adjusting movement of thewater pump impeller.

The arrangement provides the required positive drive of the camshaftwhile permitting excessive acceleration loads on the belt to be relievedby slippage of the water pump and fan portion of the drive duringexcessive torque situations. These and other advantages of the presentarrangement will be more thoroughly understood from the followingdescription of a preferred embodiment, taken together with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a pictorial view of an internal combustion engine havingcamshaft and accessory drive means according to the invention;

FIG. 2 is a front view of the engine of FIG. 1 showing the belt andpulley drive arrangement and details of the adjustable water pump; and

FIG. 3 is a cross-sectional view taken generally in the plane indicatedby the line 33 of FIG. 2 and showing the application of the water pumpto the engine cylinder block.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings inmore detail, numeral generally indicates an internal combustion enginehaving a cylinder block 12 in which is rotatably mounted a crankshaft14. A cylinder head 16 is secured to the upper portion of block 12,closing the upper ends of the engine cylinders 18 and rotatably mountingan overhead camshaft 20. The interior portion of the cylinder block 12includes a coolant cavity 22 through which cooling liquid is passed forcooling the cylinders. Coolant cavity 22 connects with passages (notshown) in the cylinder head for cooling portions thereof in aconventional manner.

Crankshaft 14 has a toothed pulley 24 mounted on one end thereof whichextends from the front of the engine block. Camshaft extends parallel tocrankshaft l4 and has a second toothed pulley 26 mounted at one endthereof and in alignment with the crankshaft pulley 24.

Intermediate the two pulleys is a water pump 28 mounted on the front ofthe engine block so as to close an opening from the coolant cavity 22.The water pump carries an impeller 30 located inside the cavity 22 andsecured to the end of a rotatable shaft 32. The shaft extends through aseal 34 and bearing 36 to connect with a drive pulley 38 carried on theshaft. An inlet connection 40 is adapted to receive water from anexternal source to be delivered by rotation of the impeller 30 directlyinto the coolant cavity 22. Clearance is provided within the coolantcavity to permit lateral movement of the water pump on its mounting,such movement being provided for by slotted openings 42 and extendedgasketing surfaces 44 of the water pump housing. Bolts 46 are utilizedto secure the water pump in any desired position within its range oflateral adjustment.

On the front of pulley 38 there is secured a fan 48, which is adaptedfor moving air through the radiator of a vehicle in which the engine maybe mounted. Pulley 38 includes on its periphery a plurality oflongitudinally spaced annular vee grooves 50 for a purpose to besubsequently described.

A drive belt 52 is provided to drivingly interconnect pulleys 24, 26 and38 and thereby provide for driving the camshaft, water pump and fan fromthe crankshaft. The interior surface of belt 52 is provided with cogs orteeth 54 which engage the toothed surfaces of pulleys 24 and 26 so as topositively time the camshaft rotation with respect to that of thecrankshaft. The water pump and fan drive pulley 38 engages the outersurface 56 of belt 52 which includes a plurality of longitudinallyextending ridges and grooves having vee-angled sides which mate with thevee grooves 50 of the pulley 38 so as to provide a relatively large loadcarrying drive surface in spite of the relatively short length for whichbelt. 52 wraps around pulley 38.

In operation, the crankshaft positively drives the camshaft by means ofthe toothed portions of belt 52. In addition, the water pump and fan aredriven through their engagement with the grooved back of belt 52. Propertension of the drive belt is maintained through manual lateraladjustment of the position of the water pump on the engine cylinderblock in the manner previously indicated. The amount of tension may beselected to drive the water pump and fan at desired normal operatingspeeds but to permit the belt to slip under extreme loads such as may becaused by fast engine accelerations when the belt loadings mightotherwise become excessive.

While the invention has been described by means of a specificembodiment, it should be understood that numerous changes could be madewithin the scope of the inventive concepts disclosed.

I claim:

1. An internal combustion engine of the type having a cylinder blockmounting a crankshaft and an overhead camshaft for rotation on coplanaraxes, said block containing a coolant cavity for the circulation ofcooling fluid therethrough, said engine including a toothed pulleymounted on said crankshaft at one end of said block a second toothedpulley mounted on said camshaft and aligned with said first toothedpulley,

a water pump mounted on said one end of said block and arranged todeliver cooling fluid into said coolant cavity, said water pump having adrive pulley including a plurality of annular ridges and grooves anddisposed generally intermediate and in alignment with said first andsecond toothed pulleys, the position on said block of said water pumpand grooved pulley being adjustable to a limited extend in a directiongenerally transverse to the plane of said crankshaft and camshaft axesand a drive belt having a toothed interior surface in driving engagementwith said first and second toothed pulleys and an exterior surfacehaving longitudinal ridges and grooves mating with the ridges andgrooves of said water pump drive pulley and in driving engagementtherewith, whereby said camshaft is positively driven by said drivebelt, said water pump is nonpositively driven by said drive belt and thetension on said belt may be adjusted by lateral adjustment of theposition of said water pump on said block.

2. An internal combustion engine of the type having a cylinder blockmounting a crankshaft and an overhead camshaft for rotation on coplanaraxes, said block including a coolant cavity for the circulation ofcooling liquid therethrough, said engine including a first toothedpulley mounted on said crankshaft at one end of said block,

a second toothed pulley mounted on said camshaft and aligned with saidfirst toothed pulley,

a water pump mounted on said one end of said block and having animpeller extending into said coolant cavity, said impeller beingarranged to deliver cooling fluid directly into said coolant cavity, theposition of said water pump on said block being adjustable to a limitedextent in a direction generally transverse to the plane of saidcrankshaft and camshaft axes, clearance being provided within saidcylinder block for the necessary lateral movement of said impeller onaccount of such adjustment,

a drive pulley carried on said water pump and drivably connected withsaid impeller, said drive pulley having a plurality of annular ridgesand grooves and being disposed generally intermediate and in alignmentwith said first and second toothed pulleys,

a fan drivably secured to said drive pulley for rotation therewith, and

a drive belt having a toothed interior surface in driving engagementwith said first and second toothed pulleys and an exterior surfacehaving longitudinal ridges and grooves mating with the ridges andgrooves of said water pump and fan drive pulley and in drivingengagement therewith, whereby said camshaft is positively driven by saiddrive belt, said water pump and fan are nonpositively driven by saiddrive belt and the tension on said drive belt may be adjusted by lateraladjustment of the position of said water pump on said block.

1. An internal combustion engine of the type having a cylinder blockmounting a crankshaft and an overhead camshaft for rotation on coplanaraxes, said block containing a coolant cavity for the circulation ofcooling fluid therethrough, said engine including a toothed pulleymounted on said crankshaft at one end of said block a second toothedpulley mounted on said camshaft and aligned with said first toothedpulley, a water pump mounted on said one end of said block and arrangedto deliver cooling fluid into said coolant cavity, said water pumphaving a drive pulley including a plurality of annular ridges andgrooves and disposed generally intermediate and in alignment with saidfirst and second toothed pulleys, the position on said block of saidwater pump and grooved pulley being adjustable to a limited extend in adirection generally transverse to the plane of said crankshaft andcamshaft axes and a drive belt having a toothed interior surface indriving engagemenT with said first and second toothed pulleys and anexterior surface having longitudinal ridges and grooves mating with theridges and grooves of said water pump drive pulley and in drivingengagement therewith, whereby said camshaft is positively driven by saiddrive belt, said water pump is nonpositively driven by said drive beltand the tension on said belt may be adjusted by lateral adjustment ofthe position of said water pump on said block.
 2. An internal combustionengine of the type having a cylinder block mounting a crankshaft and anoverhead camshaft for rotation on coplanar axes, said block including acoolant cavity for the circulation of cooling liquid therethrough, saidengine including a first toothed pulley mounted on said crankshaft atone end of said block, a second toothed pulley mounted on said camshaftand aligned with said first toothed pulley, a water pump mounted on saidone end of said block and having an impeller extending into said coolantcavity, said impeller being arranged to deliver cooling fluid directlyinto said coolant cavity, the position of said water pump on said blockbeing adjustable to a limited extent in a direction generally transverseto the plane of said crankshaft and camshaft axes, clearance beingprovided within said cylinder block for the necessary lateral movementof said impeller on account of such adjustment, a drive pulley carriedon said water pump and drivably connected with said impeller, said drivepulley having a plurality of annular ridges and grooves and beingdisposed generally intermediate and in alignment with said first andsecond toothed pulleys, a fan drivably secured to said drive pulley forrotation therewith, and a drive belt having a toothed interior surfacein driving engagement with said first and second toothed pulleys and anexterior surface having longitudinal ridges and grooves mating with theridges and grooves of said water pump and fan drive pulley and indriving engagement therewith, whereby said camshaft is positively drivenby said drive belt, said water pump and fan are nonpositively driven bysaid drive belt and the tension on said drive belt may be adjusted bylateral adjustment of the position of said water pump on said block.